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ContinuousWave: Small Boat Electrical
Cost Effective Battery
|Author||Topic: Cost Effective Battery|
posted 08-20-2009 10:38 PM ET (US)
This year, I bought a 2004 130 Sportwith a Gel Tech 8G24 battery. The battery is probably original. Starting is a bit sluggish. The tach backlight dims considerably. I feel that it is time to get a new battery. This Gel Tech retails $300. Does anyone have a suggestion for a cost effective battery that will be used only for starting and charging accessories like a handheld GPS receiver and VHF?
posted 08-21-2009 07:41 AM ET (US)
Get a flooded cell lead acid marine cranking battery. Interstate is a good brand.
posted 08-21-2009 03:19 PM ET (US)
I am a strong believer in Optima Batteries. Which type you get (Red, Blue, or Yellow top) will depend on your usage. It sounds like you use it primarily just for starting. In that case I would get a Red top.
I have a friend that has had the same Optima Red top battery for ten years. It has occupied the battery tray in probably seven different cars in that time frame and it still works as good as it did the day he bought it.
posted 08-22-2009 10:08 PM ET (US)
I'm a strong believer that most batteries are good for a certain amount of time then they are not dependable. I fish offshore (15 miles) and really want my batteries to produce when it's time to come back in. My opinion and it is just an opinion, is 3 years and I want new batteries. I buy Wal mart's group 24 battery for around $60. They have a replacement policy that I have used before and I like the service that comes with the battery.
posted 08-23-2009 09:15 AM ET (US)
My observation is that many proponents of using a sealed battery for a marine application like to imply that those batteries will have longer life than other types of marine batteries. The popular absorbent glass mat (AGM) construction battery is a sealed battery, and is often recommended. The irony of that recommendation is that sealed batteries are not known for longer life. A sealed battery provides some conveniences and advantages for certain applications, but one of those is not longer life. A conventional flooded-cell lead-acid battery to which water can be added can have a very long life span if properly cared for and maintained. It is routine for quality flooded-cell batteries to last 10 years.
A further irony is that most AGM batteries are sold with a shorter warranty period than many flooded cell batteries. I believe this reflects the manufacturer's awareness of their potential for long life.
The useful life span of a battery is very much influenced by the nature of its use, how it is cared for, and what electrical demands are placed on it.
It is difficult to make hard and fast rules about what battery will be the most cost effective. If a $360 battery lasts for ten years, is it more cost effective than a $75 battery that last for two years? I suspect that you will find more boats have a two-year-old $75 battery than have a ten-year-old $360 battery.
posted 08-23-2009 10:27 AM ET (US)
I strongly disagree with jimh's statements that an AGM battery won't have a longer life in real worl marine conditions than a flooded battery. My personal experience runs very much to the contrary. I have used flooded and AGM batteries on a number of boats over my lifetime, and the AGM batteries have lasted significantly longer. I have gotten up to 7 years' use out of AGM batteries on boats I have owned without a deterioration in performance.
I believe AGM batteries will last longer in real world marine conditions primarily due to the fact that they do not discharge during periods of non-use the way flooded batteries do. Deep dicharging a battery (even for deep cycle batteries made for such deep discharge) dramatically shortens its life versus a battery kept at 100% of its charge all the time. If a boat is left for weeks at a time unused, either in winter storage or otherwise, the flooded battery will self discharge to a much higher degree than an AGM battery. It still may have enough charge to start the boat, but being kept in a state of partial discharge will shorten its life.
If you keep a high quality flooded battery perfectly maintained at all times with full cells of distrilled water, and keep it on a smart charger at all times when not using the boat to keep it fully charged without over charging, then perhaps life cycles would be similar between an AGM and a flooded battery, assuming they are both of similar quality construction. But most boat owners either can't or won't be able to keep their batteries perfectly maintained and charged 100% of the time....this is where an AGM will last longer in real world consitions for most boaters.
In a previous discussion on this topic jimh once linked an article on industrial batteries that showed no life advantage for AGM batteries over flooded. But these were industrial batteries, perfectly maintained at all times in an air conditioned lab environment with what appeared to be daily maintenance and charging. In marine applications I have found in my personal experience that AGM batteries will last significantly longer than flooded Interstate marine batteries.
Whether the additional cost of an AGM battery is worth any additional life gained is a seperate calculation that I don't have the answer to. For me, the lack of maintenance of an AGM makes them worth it, as accessing my batteries to top off water levels under my console is difficult...and letting a flooded battery get low on water will rapidly shorten its life as well.
posted 08-23-2009 10:39 AM ET (US)
John--You should read the very interesting discussion
Self-discharge of Storage Batteries
in which the notion that AGM batteries have a very significantly lower self-discharge rate than a conventional flooded cell battery is discussed. In that discussion I published some measurements I made which showed that the difference in self-discharge rates was not particularly compelling. Most claims made are not backed with any sort of data. In fact, as far as I can tell, my published measurements are about the only real data on this topic. Most anecdotal reports are entirely devoid of any data, and most manufacturer's claims are unsupported with any data. People keep repeating meaningless adjectives like "better" without any facts backing them up.
posted 08-23-2009 11:30 AM ET (US)
Thanks for the link. I had seen that post, in fact I had added to the discussion, but I had not seen the conclusion to your four month test. It is an interesteing data point.
However, I continue to believe, based on my personal experience, that in real world marine conditions using common available brands of marine batteries, I will continue to find the typical AGM battery to last longer, and discharge less, than an Interstate flooded battery. I don't base this on vague advertising of AGM batteries, but rather my own personal experience. If I leave a boat unattended for 2-3 months, the flooded battery will be noticeably discharged, making turning over the motor more difficult than when it was fully charged. In similar situations using an AGM battery it turns the motor right over as if it just came off the charger. This was using similar CCA rated batteries. I have also found the AGM batteries I have owned to consistently last longer than the flooded batteries I have owned. As you point out, the additional cost of an AGM may not be justified by a gain in battery life, even if such a gain in battery life was proveable. When I buy AGM batteries it is in part due to other attributes (lower maintenance, faster recharging, etc) in addition to longer life.
Perhaps my boating in hot Florida & south Georgia makes a difference in my experiences over the past 15 years with AGM batteries being different from your test done in a closet at room temperature. But for whatever the reason, my own experiences with a number of batteries and a number of boats point to longer life and lower self discharge with the AGM batteries I have owned. (My family owns 6 boats from 13 to 35 feet with batteries ranging from 6 volt flooded to 12 volt AGM. I mention this only to make the point that I'm not basing my observations on one particular battery in one particular boat).
My experiences are consiistent with virtually everything I have read or heard from boaters who have owned AGM batteries, and written reports in West Marine Advisor, etc., with the exception of your four month test and your general skepticism of these batteries.
posted 08-23-2009 11:34 AM ET (US)
John - don't bother trying - Jim will beat you to death with his data and it really does not matter what the industry has chosen. Yellowfin, Intrepid and SeaVee - all mfrs of high end boats that use batteries heavily on the open ocean, install AGM's. Mercury requires an AGM for the heavy demands of the Verado. An AGM is clearly the choice if you want the best application for offshore and are running baitwells, radar, VHFs, AP's and other heavy demands.
That being said, the OP asked for a economical solution and I would agree - a properly maintained lead acid is a good choice if you want to care for them.
But if you want to mount the batt where it's hard to get to, you may flatten the battery every now and then for what ever reason, and like the fact that they don't discharge in storage, an AGM is the way to go.
My company installs marine electronics - way before I got there, they installed and sold Odyssey AGM batteries - when I asked why - the answer was - "cause we don't have to go back and replace them and they take abuse well that most boaters give them."
I run 4 Odyssey PC1500DT batteries for my offshore use. I swap every 4 years, no matter what condition they are in.
posted 08-23-2009 01:02 PM ET (US)
"...don't bother trying - Jim will beat you to death with his data...."
Glen and I live in different worlds. Glen lives in the world where anecdotal reports trump everything, and especially when they are his anecdotes.
posted 08-23-2009 01:08 PM ET (US)
If the test criterion is three months in tropical sunlight, your results (from a comparison of sealed and vented batteries) will be different than at room temperature in a closet. Sealed batteries are also popular under the hood of cars, where the ambient temperature can be 200-degrees.
In the lazarette of my Boston Whaler boat stored indoors for the winter, when my batteries undergo six months of non-use, the self-discharge rate is very low and a one or two percent difference that might be obtained by spending four or five times as much on the battery is not significant.
David, who asked about cost effective batteries, probably does not want to spend a fair percentage of the value of his 13-foot boat on gold-plated batteries, but you are free to encourage him to do so, nevertheless.
posted 08-23-2009 01:21 PM ET (US)
not anecdotal reports Jim, industry moves and trends...when 4 mfrs I repect move to AGM's (of any type), I see that as hard data and good enuf for me.
posted 08-25-2009 02:59 PM ET (US)
Here's a question; where the heck does a boater get distilled water? Once he obtains it, where does he store it?
When I'm topping off the batteries on the trawler, it's usually when I have some down-time, which is usually when I'm anchored out in some remote spot, with no shoreside services, and frequently not even any paved roads. I suppose I could store away a bunch of gallons of distilled water, but what typically ends up happening is I just use the potable water to top off the batteries. This has to be done every month or so, and the boat has a total of seven deep cycle batteries, so each top off uses at least a gallon.
On my Whaler, the water consumption rate is much less and the refilling less frequent. However, the available storage space is MUCH less. I can not carry around even a single gallon of distilled water.
A sealed battery would eliminate this headache all together, which would be very nice, and, like a lot of things on the boat, it's hard to put a dollar amount on the convenience factor.
posted 08-25-2009 10:09 PM ET (US)
I always get my distilled water at either a drug or grocery store. For some reason the marine product makers/sellers haven't repackaged it into 16 oz. bottles yet and sell for ten times the price as Battery Replenishment Fluid (BRF). On my trawler it was stored with other fluids in the engine compartment. If my Whaler had a battery that needed it I'd fine a empty pop bottle and store it there.
posted 08-28-2009 10:50 AM ET (US)
Go to Costco and by a battery. I've found that they last as long if not longer than name marine batteries and you save a good chunk of money.
posted 08-28-2009 11:27 AM ET (US)
I buy distilled water at the grocery store. It's around $1.15 a gallon. I buy it in quantity just in case of hurricane or other natural disaster. It stores for a long time because it is distilled with no impurities like so called "Spring" water that comes from who knows where. Cheap insurance for basic needs. It works better in steam irons to prevent clogging also.
posted 09-06-2009 07:48 AM ET (US)
I tend to agree that flooded cell batteries cannot be beat when all consideration of cost, performance, and longevity are considered.
Only thing I would add is that I am a strong proponent of combination starting/deep-cycle batteries. The cost difference from a pure starting battery is minimal or none. And they are better suited to (at least some) marine usage patterns, where accessories may be run extensively with the engine off. This is not typical in a car. I believe it is common knowledge that starting-only batteries have their lives shortened considerably if they are allow to frequently discharge, even partially.
posted 09-06-2009 08:31 AM ET (US)
One parameter which has not been considered in this discussion is the battery size or form factor and its relationship to battery cranking amperes. To get the most cranking amperes in the least space, the flooded cell cranking battery is probably the best choice. If your vessel installation does not impose a limit on the battery size, you can find some nice dual-purpose batteries with rather high cranking ampere output, but they will tend to be in larger cases than an equivalent cranking battery. They will also cost more.
Glen repeatedly cites the VERADO motor as requiring an AGM battery and implies that we all must be bound by this or at least pay tribute to it as great advice for our own installations. However, the VERADO propulsion system--it is not just an outboard engine--has distinctly different requirements than most small boat outboard engines. I explain:
The VERADO needs a huge amount of electrical current to operate its electrical boost pump for its power steering system. This is especially important around the dock where very rapid steering maneuvering may be needed. The electrical steering boost pump can draw 60-amperes from the battery. It does this at a time when the engine speed is very low, and the charging current available from the engine charging system is at its lowest. This puts a lot of load on the battery.
Consider this situation: the Verado-powered boat has been sitting for a few weeks, so the battery charge may be less than fully charged. You hop aboard and start the engine. Engine starting is a big current drain on the battery. Next you turn on all the accessories--more load. The engine speed is at idle, and charging current is low. Next we turn the wheel and begin to maneuver to leave the mooring or dock. More drain on the battery, and a heavy drain, not just an ampere or two. Now we have to run at idle speed for several miles in a NO-WAKE zone. More drain on the battery from maneuvering, all the while with the engine only able to provide limited charging current due to low speed.
By the time we reach open water where we can increase engine speed, there can be considerable drain on the battery. If using an AGM, the battery will be more tolerant of these deep discharges than other types of batteries.
Next we hit the throttle and get on plane. We need to replace all the stored electrical energy in the battery. Again, the AGM helps because it can typically absorb more charging current than conventional batteries. So when we have 50-amperes of charging current available from the engine, the AGM battery can use it. An AGM battery can absorb high charging currents.
When viewed in the perspective of these conditions, the AGM battery is a good solution for a Verado-powered boat, and given that Mercury requires use of an AGM battery, these is nothing in the way of an argument which could be made against using an AGM battery with a Verado. However, just because an AGM battery is a good fit for a Verado, and just because Mercury requires that an AGM battery be used with a Verado, does not mean that the AGM battery has been anointed as the only cost effective battery that could ever be considered for use on a small boat.
In the situation we are talking about here, a 13-foot boat, the value of the whole boat might be in the range of $3,750. It hardly seem cost effective to spend ten-percent of the total value of the boat on a single battery. I don't think it is necessary to install a premium AGM battery in every small boat in the world. That's my point here. If four AGM batteries are needed to keep boats with twin or triple or quadruple Verado engines running, that is a great solution for those boats, but it does not become a binding solution for everyone.
posted 09-06-2009 11:54 AM ET (US)
Again, a load of crap. i don't care what you buy. I have repeatedly said that a lead acid battery that you can maintain is a good choice. You choose an AGM if you are going to cycle the battery a lot, don't want to check the water, like a low discharge rate and like that it recharges faster than a lead acid battery.
Nothing more.. Do a search on the web for the Professional Boatbuilder magazine article called "Running The Numbers" - regarding batteries and efficiency. - It in the August 2009 issue.
posted 09-06-2009 04:39 PM ET (US)
Glen--Please let me give you a bit of advice. If you want to point to an article on the web, then you should do the searching around with GOOGLE to find it, not us.
As for everything I said about the Verado, its thirst for electrical energy at low speeds, and its need to use an AGM battery, it is all completely true. If not, why would Mercury insist on an AGM battery?
Oh, I see Glen slipped in another misconception about AGM batteries: a low discharge rate. There is absolutely nothing about an AGM battery construction that gives a low discharge rate. This point was made quite clear in another discussion. Low self-discharge comes from the purity of the lead used in the battery. It does not come from being built using absorbent glass mat.
Some AGM batteries may have very high purity lead and this will give them a low self-discharge rate, but there is no guarantee that those cheapo AGM batteries imported from China--where most of them are made--will intrinsically have a significantly better self discharge rate just because they are AGM type.
For a good discussion about what engenders low self-discharge rates in lead-acid batteries, see
Self-discharge of Storage Batteries
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